Civil Engineering Reference
In-Depth Information
these applications are already found in the market. Nanocomposites are currently used
in a number of i elds and new applications are continuously sought at er. Some of the
modern applications of nanocomposites include:
•
h in-i lm capacitors for computer chips
•
Solid polymer electrolytes for batteries
•
Automotive engine parts and fuel tanks
•
Impellers and blades
•
Oxygen and gas barriers
•
Food packaging
h e attractiveness of polymer nanocomposites resides in the potential of adding
nanometer-sized i llers to dramatically raise the mechanical, thermal, barrier and
l ame-retardant properties, without increasing the specii c gravity or reducing the
transparency of the nanocomposites relative to the base material [1-4]. Recently, signif-
icant attention has been given towards the development and investigation of polymer
nanocomposites with the expectation that this can lead to lighter and better materials
for engineering applications [5-7].
Among the various types of nanoi llers, nanocellulose is gaining importance due
to its renewable nature, ecofriendliness and low cost. Several research works are now
being carried out incorporating nanocellulose as i ller in dif erent polymer matrices to
develop new products with enhanced properties at a lower cost.
h is chapter will focus on
in-situ
polymerized cellulose nanocomposites, as this
technique is relatively new and becoming popular among the material scientists due to
added advantages over conventional nanocomposite fabrication techniques like solu-
tion dispersion or melt mixing.
5.2
Cellulose as Filler in Polymer Matrix Composites
Cellulose is the most abundant biopolymer present in nature [8]. h is structural mate-
rial is naturally organized as microi brils which are linked together to form cellulose
i bers.
5.2.1
Source
It is biosynthesized by a number of living organisms ranging from higher to lower
plants, some amoebae, sea animals, bacteria and fungi [9]. Cellulose i bers can be clas-
sii ed according to their origin and grouped into leaf: abaca, cantala, curaua, date palm,
henequen, pineapple, sisal, banana; seed: cotton; bast: l ax, hemp, jute, ramie; fruit: coir,
kapok, oil palm; grass: alfa, bagasse, bamboo; and stalk: straw (cereal). h e bast and leaf
(the hard i bers) types are most commonly used in composite applications. Plant i bers
generally used are cotton, jute, hemp, l ax, ramie, sisal, coir, henequen, and kapok. h e
largest producers of sisal in the world are Tanzania and Brazil. Henequen is produced in
Mexico whereas abaca and hemp in Philippines. h e largest producers of jute are India,
China, and Bangladesh [10].
